In the quest to find out why my car wouldn't boost past 7psi, I checked all the intake and IC piping, all the vacuum lines etc, and finally took off the BC, and the MoFo was dirty as hell. I guess there was enough dirt and gunk in there that the ball wouldn't seat against the fitting, so basically there was a free path to the wastegate actuator, thus no boost.
Moral of the story. Check and clean out your boost controller regularly.
